sal ati



United States Patent Ofifice RELAY SELECTING CIRCUIT Octavio M. Salati,Philadelphia, Pa., assignor to the United States of America asrepresented by the Secretary f the Army Application January 4, 1952,Serial No. 264,959

1 Claim. (Cl. 317137) This invention relates to relay systems and moreparticularly to relay systems for controlling a multiplicity of circuitsin accordance with a predetermined priority schedule.

The object of this invention is to provide means by which a multiplicityof circuits can be assigned a priority with respect to one another, sothat when and if two or more of said circuits are sought to be operatedby external means, either simultaneously or alternately, that associatedcircuit having the highest assigned priority will always be selected andoperated.

A further object of this invention is to provide a priority selectiverelay system for controlling a multiplicity of electrically dissociatedcircuits capable of operation in a power level completely different fromthat of the relay system.

These and other objects of the invention will appear in the followingdescription and appended claim, reference being had to the accompanyingdrawing in which a preferred embodiment of this invention is shown.

In the drawing, a three relay system is shown, but it will be apparentfrom the following description that additional relays may be added tothe system to control any number of circuits by merely repeating thecircuit shown as often as is necessary, and that any other type ofmagnetically actuated control device may be utilized in the same mannerand to perform the same functions as the relays here described. In thisapplication the term lock-in power source is used to connote the powersource required to maintain the relays in the energized state once theassociated operating coils of the relays are energized.

In the drawing, relays 2, 4 and 6 are arranged in order of descendingpriority from left to right and are placed directly below theirassociated switches 8, 10 and 12, respectively. Switches 8, 10 and 12each have one of their sides connected to a common wire 14, which isconnected to power source 16. The other sides of each of said switches8, 10 and 12 are respectively connected to operating coils 18, 20 and22, through normally closed arms 24, 26 and 28, respectively. Arm 30 isconnected to power source 15. Arm 32 is connected to power source 15,through arms 36 and 30. Arm 34 is connected to power source through arms38, 32, 36 and 30. Arm 40 is shown merely to indicate the possibility ofadding more relays to the system shown and does not function as part ofthe three relay system of the drawing.

Each relay in the system operates on the same contact sequence when itscoil is energized; therefore, only the contact sequence of relay 2 willbe explained. When coil 18 of relay 2 is energized, first the normalcontact of arms 36 and 30 is broken, then contact is made between arm 30and arm 42, and lastly, the normal contact of arms 24 and 42 is broken.

2,712,101 Patented June 28, 1955 At this point it should be noted thatswitches 8, 10 and 12 provide initiating energy to coils 18, and 22,

- respectively, but that in each case, the initiating energy is suppliedthrough normally closed contacts. Therefore, the relays must obtainlock-in energy through some other circuit or they will oscillate.Lock-in energy is supplied by power source 15 to coil 18 through arms 30and 42, to coil 20 through arms 30, 36, 32 and 44 and to coil 22 througharms 30, 36, 32, 38, 34 and 46. Thus, relay 2 provides its own completelock-in circuit once it is initially energized, relay 4 uses normallyclosed contacts of relay 2 in its lock-in circuit and relay 6 usesnormally closed contacts in both relay 2 and relay 4 to complete itslock-in circuit. Thus, the relays are effectively connected in a serieslock-in chain so that if more than one relay is energized, eithersimultaneously or alternately, only the relay closest to power source 15in the relay chain will lock-in and, in so doing, will prevent thelocking-in of all other relays more remote from power source 15 in thechain.

The external circuits operated by the relay system according to thisinvention and the relay contacts within those circuits that controlexternal circuit operation are indicated by boxes 48, 50 and 52 and areshown directly below their associated relays. It is understood that thecircuits indicated by boxes 48, 5t} and 52 are operated by relays 2, 4and 6, respectively.

Switches 8, 1d and 12 are shown as knife switches for simplicity and forease of explanation, but it is understood that they may be any type ofswitch, including the contact arms of another relay system.

In the operation of a system according to this invention some externalmeans (not shown), such as a relay system or manual operation isutilized to close one or more of switches 8, 10 and 12, eithersimultaneously or alternately. As soon as any one or all of saidswitches close, they provide paths for energizing the coils of theirassociated relays. Once the coils of the associated relays areenergized, the associated relays begin to operate on the previouslydescribed contact sequence. Then, since each relay except relay 2 isdependent on a relay less remote from power source 15 than itself, therelay closest to power source 15, in the previously described lock-inchain, will lock itself in and all other relays more remote from powersource 15 will return to their normal position.

It will be noted that relays more remote from power source 15 in thelock-in chain than the one relay which locks itself in, will oscillateas long as their associated switches remain closed. To prevent thoseoscillations from affecting the circuits indicated in boxes 48, 50 and52, the operated relay arms in circuits 48, 50 and 52 may either bemechanically interlocked or electrically interlocked to their associatedcoil circuits to prevent their operation until their associated coillocks itself in.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope hereof, it is to beunderstood that the invention is not limited to its specific embodimentsexcept as defined in the appended claim.

What is claimed is:

In a relay selecting circuit the combination comprising a lock-in powersource, a plurality of discrete relays, each of said relays having atleast a first and a second pair of normally closed contact arms, thediscrete coils in each of said relays being in circuit with the firstpair of said closed contact arms in each of said relays when said coilsare unenergized, the second pair of said closed contact arms in thefirst of said relays being in circuit with said lock-in power source,the second pair of closed contact arms of the second of said relaysbeing connected to said second pair of contact arms of said first relay,the second pair of closed contact arms of each succeeding relay of saidplurality of relays being connected to the second pair of closedcontacts of each preceding relay, an initiating power source, and aplurality of discrete switches connecting each of said relays to saidinitiating power source.

References Cited in the file of this patent UNITED STATES PATENTS LibergApr. 22, 1952

